feat: announce on Discourse support forum (#17)

## Summary

- Adds `announceOnDiscourse` module to post announcements to the NHCarrigan Discourse support forum (category 16), tagged by announcement type
- Adds `chunkContent` utility to split long announcements at paragraph/line boundaries for Discord (2000 chars), Reddit (40,000 chars), and Discourse (32,000 chars); Reddit overflows chain as nested replies, Discord as sequential messages, Discourse as sequential replies
- Refactors the announcement route to run all platforms concurrently via `Promise.allSettled`, ensuring a failure on any one platform never blocks the others, with all results reported back
- Fixes generation failure response from incorrect `201` to `500`

✨ This PR was created with love from Hikari~ 🌸

Reviewed-on: #17
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

server/src/utils/chunkContent.ts

@@ -0,0 +1,84 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+/* eslint-disable max-lines-per-function -- Multi-level split logic requires many lines. */
+/* eslint-disable max-statements -- Multi-level split logic requires many statements. */
+/* eslint-disable complexity -- Multi-level split logic has inherent branching complexity. */
+
+/**
+ * Splits content into chunks that do not exceed the given character limit.
+ * Splits preferably at paragraph boundaries, then line boundaries,
+ * then hard-cuts at the limit as a last resort.
+ * @param content - The content to chunk.
+ * @param limit - The maximum character count per chunk.
+ * @returns An array of content chunks.
+ */
+export const chunkContent = (content: string, limit: number): Array<string> => {
+  if (content.length <= limit) {
+    return [ content ];
+  }
+
+  const chunks: Array<string> = [];
+  const paragraphs = content.split("\n\n");
+  let current = "";
+
+  for (const paragraph of paragraphs) {
+    const separator = current.length > 0
+      ? "\n\n"
+      : "";
+    const combined = `${current}${separator}${paragraph}`;
+
+    if (combined.length <= limit) {
+      current = combined;
+      continue;
+    }
+
+    if (current.length > 0) {
+      chunks.push(current);
+      current = "";
+    }
+
+    if (paragraph.length <= limit) {
+      current = paragraph;
+      continue;
+    }
+
+    // Paragraph itself exceeds the limit — split by lines
+    const lines = paragraph.split("\n");
+    for (const line of lines) {
+      const lineSeparator = current.length > 0
+        ? "\n"
+        : "";
+      const combinedLine = `${current}${lineSeparator}${line}`;
+
+      if (combinedLine.length <= limit) {
+        current = combinedLine;
+        continue;
+      }
+
+      if (current.length > 0) {
+        chunks.push(current);
+        current = "";
+      }
+
+      if (line.length <= limit) {
+        current = line;
+        continue;
+      }
+
+      // Single line exceeds limit — hard-cut
+      for (let index = 0; index < line.length; index = index + limit) {
+        chunks.push(line.slice(index, index + limit));
+      }
+    }
+  }
+
+  if (current.length > 0) {
+    chunks.push(current);
+  }
+
+  return chunks;
+};